1. Field of the Invention
The present invention relates to electrical connector systems. More specifically, the present invention relates to electrical connector systems that minimize cross-talk.
2. Brief Description of Earlier Developments
The continuous increase in the operating speeds of electronic systems and the miniaturization of electrical connectors demand greater control of cross-talk. Cross-talk occurs when electromagnetic energy transmitted through a conductor in the connector causes electrical currents in the another conductor in the electrical connector. Near-end cross-talk (NEXT) travels in a direction opposite to the signal in the conductor. As an example, ANSI/EIA/TIA/568A Category 5 requirements limit pair-to-pair NEXT to -40 dB at 100 MHz. Some applications require such cross-talk performance, but measured on a power sum basis.
Various attempts have been made to control cross-talk within the connector. U.S. Pat. No. 5,562,479 describes an electrical connector in which a mating portion of the connector produces a "positive" cross-talk. Another portion of the connector arranges the conductors side-by-side in a plane to produce a "negative" cross-talk. The "negative" cross-talk cancels out the "positive" cross-talk.
U.S. Pat. No. 5,647,770 describes a modular jack in which adjacent conductor wires are crossed over for a portion of a length along an insert. The cross-talk produced in the cross-over portion cancels out the cross-talk produced in the portions of the conductor wire that are not crossed-over.
Various attempts have also been made to control cross-talk outside of the connector. British Patent Application GB 2 314 466 describes a compensation pattern on a multi-layer board (MLB) to which contacts from an electrical connector secure. The pattern uses vertically aligned arrays of conductive paths. Capacitive coupling between adjacent unlike paths produces a cross-talk that reduces the cross-talk produced by the connector. The pattern also staggers adjacent paths on a layer in order to allow coupling between non-adjacent paths.
European Patent Application number EP 0 854 664 also describes a compensation pattern on an MLB to which the electrical connector contacts connect. A portion of the conductive paths extend along one layer, while the remainder extends along another layer vertically spaced therefrom. The arrangement of the paths ensures that one path of a pair overlies at least two paths, each from a different pair.